1. Field of the Invention
The present invention relates to a pulse motor control apparatus, which permits desired setting and control of the rotational displacement and a speed pattern of a pulse motor until the prescribed displacement is covered.
2. Description of the Prior Art
As for pulse motor control systems known to date, there are included constant speed control systems (fixed frequency systems) and constant acceleration control systems (variable frequency systems).
FIG. 1 is a graph showing displacement curves obtained by a constant speed control system. This system uses an oscillator, a frequency divider, a counter and so forth, and the number of pulses required until a prescribed displacement M is covered is set by means of a digital switch, etc. A pulse motor is rotated at a constant speed for the prescribed displacement M by receiving the preset number of pulses which are supplied with a constant pulse period (a fixed frequency). In controlling the pulse motor from a relative position, the displacement therefrom to a specified position is calculated to obtain the number of pulses, and the pulse motor is driven at a constant speed to the specified position in the same manner as described above.
FIG. 2 is a graph showing displacement curves obtained by a constant acceleration control system. This system uses a variable frequency oscillator which can variably control the pulse period. With this system, the pulse motor is driven at a constant acceleration by generating, for instance, 50 pulses necessary for a prescribed displacement M, at a rate varied from 100 to 1000 pulses per second.
In the actual pulse motor control, however, displacement patterns other than the constant speed and constant acceleration displacement patterns, such as analogous displacement patterns based on a variation in the prescribed displacement and displacement patterns suited to the characteristics of the load of the pulse motor, for example, are required. Such displacement patterns cannot be freely produced with the prior art constant speed and constant acceleration control systems.